Abdomen (perhaps from Latin abdodere = to conceal, to hide; in the sense that whatever was eaten is hidden in the stomach) or belly is a body cavity lying between the chest and pelvis, limited with the diaphragm above and continuing into the pelvic cavity below.
Being the largest cavity in the human body and containing the most organs than any other cavity, the abdomen is often given much focus in medicine. It is the often the source of some of the more common as well as serious diseases that afflict humans and containing the most amount of organs, it is also more likely to be plagued with various symptoms.
Location of the Abdomen
It is often thought that the abdomen stars from the lower end of the costal cartilage meaning imaginary horizontal line that runs across the inferior borders of the last rib on either side. Actually the abdomen stars from beneath the 8th rib approximately, or more correctly, at the imaginary horizontal line that runs along in the bottom edge of the sternum (breastbone).
This means that the upper abdominal contents like the liver, stomach, and spleen are neatly tucked under the ribcage. Apart from considering the diaphragm as being the upper internal border and the imaginary line between the iliac crests of the hip bone as being the lower border, it may also help to define the abdominal cavity by its organs and structures.
Organs in the Abdomen
Stomach, the common term used for abdomen, is actually only one organ in the abdomen, lying between the esophagus (gullet) and duodenum (first part of the small intestine). The abdomen is also referred to commonly as the tummy but this term is used interchangeably between abdomen and the stomach (organ).
It is also important to realize that certain organs like the bladder in childhood and the pregnant uterus can be located or extend up into the abdominal cavity.
Strictly speaking, the following organs are defined as abdominal organs. While some parts could extend downwards into the pelvic cavity, or even protrude into the the thoracic (chest) cavity in a hernia, it still remains an abdominal organ.
- Small intestine: duodenum, jejunum, ileum
- Cecum with appendix
- Large intestine (colon) with the rectum
- Kidneys and ureters
- Adrenal glands
- Large blood vessels – abdominal part of aorta, and vena cava inferior
It is also important to remember that several back structures including vertebrae, nerves, muscles and ligaments exist in the abdominal cavity but are often considered under the back or posterior abdominal wall.
Picture 1. Abdominal organs